diff --git a/Debug/Window_practice.exe b/Debug/Window_practice.exe
index 43f80cc..4aa9ca9 100644
Binary files a/Debug/Window_practice.exe and b/Debug/Window_practice.exe differ
diff --git a/Debug/Window_practice.pdb b/Debug/Window_practice.pdb
index 348f7a3..057df45 100644
Binary files a/Debug/Window_practice.pdb and b/Debug/Window_practice.pdb differ
diff --git a/Window_practice/Debug/Main.obj b/Window_practice/Debug/Main.obj
index 94555a8..e6646d7 100644
Binary files a/Window_practice/Debug/Main.obj and b/Window_practice/Debug/Main.obj differ
diff --git a/Window_practice/Debug/Window_practice.ilk b/Window_practice/Debug/Window_practice.ilk
index ee8c681..418ac8e 100644
Binary files a/Window_practice/Debug/Window_practice.ilk and b/Window_practice/Debug/Window_practice.ilk differ
diff --git a/Window_practice/Debug/Window_practice.log b/Window_practice/Debug/Window_practice.log
index a75dc57..7f84570 100644
--- a/Window_practice/Debug/Window_practice.log
+++ b/Window_practice/Debug/Window_practice.log
@@ -1,5 +1,2 @@
   Main.cpp
-LINK : warning LNK4098: defaultlib 'MSVCRT' conflicts with use of other libs; use /NODEFAULTLIB:library
-LINK : warning LNK4098: defaultlib 'LIBCMT' conflicts with use of other libs; use /NODEFAULTLIB:library
-glew32s.lib(glew.obj) : warning LNK4099: PDB '' was not found with 'glew32s.lib(glew.obj)' or at ''; linking object as if no debug info
   Window_practice.vcxproj -> C:\dev\Glfw_Practice\c++\Window_practice\Debug\Window_practice.exe
diff --git a/Window_practice/Debug/Window_practice.tlog/link.read.1.tlog b/Window_practice/Debug/Window_practice.tlog/link.read.1.tlog
index aaab8f2..d98202f 100644
Binary files a/Window_practice/Debug/Window_practice.tlog/link.read.1.tlog and b/Window_practice/Debug/Window_practice.tlog/link.read.1.tlog differ
diff --git a/Window_practice/Debug/vc142.idb b/Window_practice/Debug/vc142.idb
index 202cb9e..36c22ed 100644
Binary files a/Window_practice/Debug/vc142.idb and b/Window_practice/Debug/vc142.idb differ
diff --git a/Window_practice/Debug/vc142.pdb b/Window_practice/Debug/vc142.pdb
index faaba5c..1e30569 100644
Binary files a/Window_practice/Debug/vc142.pdb and b/Window_practice/Debug/vc142.pdb differ
diff --git a/Window_practice/src/Main.cpp b/Window_practice/src/Main.cpp
index b36f5ac..9476c93 100644
--- a/Window_practice/src/Main.cpp
+++ b/Window_practice/src/Main.cpp
@@ -1,10 +1,30 @@
 #include <GL/glew.h>
 #include <GLFW/glfw3.h>
+
 #include <iostream>
 #include <fstream>
 #include <string>
 #include <sstream>
 
+#define ASSERT(x) if(!(x)) __debugbreak();
+#define GLCall(x) GLClearError();\
+    x;\
+    ASSERT(GLLogCall(#x, __FILE__, __LINE__))    
+
+static void GLClearError() {
+    while (glGetError() != GL_NO_ERROR);
+}
+
+static bool GLLogCall(const char* function, const char* file, int line) {
+    while (GLenum error = glGetError()) {
+        std::cout << "[OpenGL Error] (" << error << "): "
+            << function << " " << file << ":" << line << std::endl;
+        return false;
+    }
+
+    return true;
+}
+
 struct ShaderProgramSource {
     std::string VertexSource;
     std::string FragmentSource;
@@ -125,22 +145,20 @@ int main(void){
         2, 3, 0
     };
 
-
-
     //Vertex buffer(s)
     unsigned int buffer;
-    glGenBuffers(1, &buffer); //number of buffer to generate
-    glBindBuffer(GL_ARRAY_BUFFER, buffer); //binding the buffer
-    glBufferData(GL_ARRAY_BUFFER, 6 * 2 * sizeof(float), positions, GL_STATIC_DRAW);
+    GLCall(glGenBuffers(1, &buffer)); //number of buffer to generate
+    GLCall(glBindBuffer(GL_ARRAY_BUFFER, buffer)); //binding the buffer
+    GLCall(glBufferData(GL_ARRAY_BUFFER, 6 * 2 * sizeof(float), positions, GL_STATIC_DRAW));
 
-    glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);
+    GLCall(glEnableVertexAttribArray(0));
+    GLCall(glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0));
 
     //index buffer setup
     unsigned int ibo; //index buffer object
-    glGenBuffers(1, &ibo); 
-    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo); //binding the buffer
-    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indecies, GL_STATIC_DRAW);
+    GLCall(glGenBuffers(1, &ibo)); 
+    GLCall(glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo)); //binding the buffer
+    GLCall(glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indecies, GL_STATIC_DRAW));
 
     ShaderProgramSource source = ParseShader("res/shaders/Basic.shader");
     std::cout << "VERTEX" << std::endl;
@@ -151,23 +169,23 @@ int main(void){
     unsigned int shader = CreateShader(source.VertexSource, source.FragmentSource);
     glUseProgram(shader);
 
-    glBindBuffer(GL_ARRAY_BUFFER, 0); //unbinding the buffer
+    GLCall(glBindBuffer(GL_ARRAY_BUFFER, 0)); //unbinding the buffer
 
    //Main loop
     while (!glfwWindowShouldClose(window)){
         /* Render here */
-        glClear(GL_COLOR_BUFFER_BIT);
+        GLCall(glClear(GL_COLOR_BUFFER_BIT));
 
-        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
+        GLCall(glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr));
 
         /* Swap front and back buffers */
-        glfwSwapBuffers(window);
+        GLCall(glfwSwapBuffers(window));
 
         /* Poll for and process events */
-        glfwPollEvents();
+        GLCall(glfwPollEvents());
     }
 
-    glDeleteProgram(shader);
+    GLCall(glDeleteProgram(shader));
 
     glfwTerminate();
     return 0;